Detection of Arsenic in the Atmospheres of Dying Stars

TL;DR

This study detects arsenic in the atmospheres of hot white dwarfs using ultraviolet spectroscopy, revealing similar arsenic levels in some stars and suggesting radiative levitation as a supporting mechanism.

Contribution

It reports the first detection of arsenic in the atmospheres of multiple hot white dwarfs and compares arsenic abundances across different star types, highlighting potential supporting mechanisms.

Findings

Arsenic detected in three hot DA white dwarfs.

Similar arsenic abundances in DA stars suggest radiative levitation.

Variation in arsenic levels in DO stars indicates additional atmospheric processes.

Abstract

We report the detection of As V resonance lines observed in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectra of three hot DA white dwarfs: G191-B2B, WD0621-376, and WD2211-495. The stars have effective temperatures ranging from 60,000 K to 64,000 K and are among the most metal-rich white dwarfs known. We measured the arsenic abundances not only in these stars, but also in three DO stars in which As has been detected before: HD149499B, HZ21, and RE0503-289. The arsenic abundances observed in the DA stars are very similar. This suggests that radiative levitation may be the mechanism that supports arsenic. The arsenic abundance in HZ21 is significantly lower than that observed in HD149499B, even though the stars have similar atmospheric parameters. An additional mechanism may be at play in the atmospheres of these two DO stars.